Photovoltaic cells for converting sunlight into electrical energy have been traditionally made of crystalline silicon. However, thin film amorphous silicon photovoltaic cells have been found to be more economically feasible from the standpoint of manufacturing costs. However, while more economically feasible than the production of crystalline silicon cells, the production of amorphous silicon cells is still quite costly.
One of the most important parameters in any resulting amorphous silicon cell is the amount of the active area of the cell which is exposed to the light. Typically, electrical connections which are necessary for the operation of the cell also block transmission of the light into the active portions of the cell. The electrical connections are generally opaque and are located between the light incident face of the cell and the active semiconductor material.
One prior art photovoltaic cell uses a plurality of point electrical contacts to a first electrode material layer which has been previously deposited onto a substrate. The point contacts are positioned in a spaced-apart relation across the surface of the substrate and extend through deposited semiconductor material. A plurality of individual pads are deposited adjacent to the deposited semiconductor material to form back electrodes. Each pad is electrically isolated from the other pads and the point contacts. First and second sets of interdigiting fingers electrically connect the point contacts and the pads, respectively. In this way, the bulk of the electrical connections are made on the back of the cell with only the point contacts in the front, resulting in an increased active area on the light incident surface of the cell.
However, electrical connections in and between such photovoltaic cells cannot be made quickly or inexpensively. Furthermore, such electrical connections should be of sufficiently low resistance to conduct electricity through and between the cells for maximum current collection. Problems arise in prior art photovoltaic cells and panels due to the relatively high power losses in thin wires or grids used for electrical connection.